From 7dcba5b696076481deb43295ec721f253adf2d5c Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Thu, 10 Mar 2022 12:17:36 +0000
Subject: [PATCH] code-cleanup and copyright notices

---
 gram/frontend/wishbone.py | 49 +++++++++++++++++++++++++--------------
 1 file changed, 31 insertions(+), 18 deletions(-)

diff --git a/gram/frontend/wishbone.py b/gram/frontend/wishbone.py
index 611be50..a68e8cc 100644
--- a/gram/frontend/wishbone.py
+++ b/gram/frontend/wishbone.py
@@ -1,18 +1,32 @@
 # This file is Copyright (c) 2020 LambdaConcept <contact@lambdaconcept.com>
 # License: BSD
+# Copyright (c) 2020 LambdaConcept <contact@lambdaconcept.com>
+# Copyright (c) 2021 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
+#
+# Code from LambaConcept is Licensed BSD
+# Code from Luke Kenneth Casson Leighton is Licensed LGPLv3+
+#
+# Modifications for the Libre-SOC Project funded by NLnet and NGI POINTER
+# under EU Grants 871528 and 957073
 
 from math import log2
 
-from nmigen import *
+from nmigen import (Module, Elaboratable, Signal, Repl)
 from nmigen.utils import log2_int
 
 from nmigen_soc import wishbone
 from nmigen_soc.memory import MemoryMap
 from lambdasoc.periph import Peripheral
 
-
+# XXX
+# WARNING - THIS CODE CANNOT COPE WITH WISHBONE 4.0 PIPELINE MODE
+# THE ADDRESS MAY CHANGE AFTER EACH STB AND THIS IS AN ASSUMPTION
+# FROM WISHBONE 3.0 CLASSIC.  USE THE COMPATIBILITY MODE stall=cyc&~ack
+# XXX
 class gramWishbone(Peripheral, Elaboratable):
-    def __init__(self, core, data_width=32, granularity=8):
+    def __init__(self, core, data_width=32, granularity=8,
+                             features=frozenset()):
+
         super().__init__(name="wishbone")
 
         self.native_port = core.crossbar.get_native_port()
@@ -29,11 +43,12 @@ class gramWishbone(Peripheral, Elaboratable):
 
     def elaborate(self, platform):
         m = Module()
+        cmd = self.native_port.cmd
+        wdata = self.native_port.wdata
+        rdata = self.native_port.rdata
 
         # Write datapath
-        m.d.comb += [
-            self.native_port.wdata.valid.eq(self.bus.cyc & self.bus.stb & self.bus.we),
-        ]
+        m.d.comb += wdata.valid.eq(self.bus.cyc & self.bus.stb & self.bus.we)
 
         ratio_bitmask = Repl(1, log2_int(self.ratio))
 
@@ -46,44 +61,42 @@ class gramWishbone(Peripheral, Elaboratable):
         with m.Switch(self.bus.adr & ratio_bitmask):
             for i in range(self.ratio):
                 with m.Case(i):
-                    m.d.comb += self.native_port.wdata.we.eq(Repl(sel, self.bus.granularity//8) << (self.ratio*i))
+                    m.d.comb += wdata.we.eq(Repl(sel, self.bus.granularity//8) << (self.ratio*i))
 
         with m.Switch(self.bus.adr & ratio_bitmask):
             for i in range(self.ratio):
                 with m.Case(i):
-                    m.d.comb += self.native_port.wdata.data.eq(self.bus.dat_w << (self.bus.data_width*i))
+                    m.d.comb += wdata.data.eq(self.bus.dat_w << (self.bus.data_width*i))
 
         # Read datapath
-        m.d.comb += [
-            self.native_port.rdata.ready.eq(1),
-        ]
+        m.d.comb += rdata.ready.eq(1)
 
         with m.Switch(self.bus.adr & ratio_bitmask):
             for i in range(self.ratio):
                 with m.Case(i):
-                    m.d.comb += self.bus.dat_r.eq(self.native_port.rdata.data >> (self.bus.data_width*i))
+                    m.d.comb += self.bus.dat_r.eq(rdata.data >> (self.bus.data_width*i))
 
         with m.FSM():
             with m.State("Send-Cmd"):
                 m.d.comb += [
-                    self.native_port.cmd.valid.eq(self.bus.cyc & self.bus.stb),
-                    self.native_port.cmd.we.eq(self.bus.we),
-                    self.native_port.cmd.addr.eq(self.bus.adr >> log2_int(self.bus.data_width//self.bus.granularity)),
+                    cmd.valid.eq(self.bus.cyc & self.bus.stb),
+                    cmd.we.eq(self.bus.we),
+                    cmd.addr.eq(self.bus.adr >> log2_int(self.bus.data_width//self.bus.granularity)),
                 ]
 
-                with m.If(self.native_port.cmd.valid & self.native_port.cmd.ready):
+                with m.If(cmd.valid & cmd.ready):
                     with m.If(self.bus.we):
                         m.next = "Wait-Write"
                     with m.Else():
                         m.next = "Wait-Read"
 
             with m.State("Wait-Read"):
-                with m.If(self.native_port.rdata.valid):
+                with m.If(rdata.valid):
                     m.d.comb += self.bus.ack.eq(1)
                     m.next = "Send-Cmd"
 
             with m.State("Wait-Write"):
-                with m.If(self.native_port.wdata.ready):
+                with m.If(wdata.ready):
                     m.d.comb += self.bus.ack.eq(1)
                     m.next = "Send-Cmd"
 
-- 
2.30.2